A user interface (UI), in the industrial design field of human-machine interaction, is the space where interactions between humans and machines occur. The goal of interactions between a human, often referred to as a “user”, and a machine at the user interface is user's control of the machine and its operations (e.g., through user input) and machine feedback (e.g., through program output). A graphical user interface (GUI) is a type of user interface that allows users to interact with software applications executing on electronic or computing devices through multimedia objects (e.g., images, videos, audios, etc.) rather than purely text commands.
In addition to stationary devices (e.g., desktop computers), mobile devices (e.g., mobile telephones or tablet computers) are increasingly able to access various sources (e.g., sources on the Internet) to download data representing user-consumable content, such as games, audio, video, images, executables, books, and so on. Users can personalize content on their mobile as well as stationary devices with user interface customization capabilities.